Spotting, Whats Going On?

Hello ladies, i am new to this site and i have a very important question. Okay so i currently have a one year old little boy and I've been married to my husband for a year now. So for the past three days I have been spotting on and off . Meaning i only see blood when i wipe "TMI I KNOW" lol but today the blood is COMPLETELY GONE, and thats unusual for me since my period is pretty regular and i usually have a medium to heavy flow for five days straight... Me and my husband use the withdrawal method for birth control and idk what this could mean